Replacing 5.9 block with 6.7

I have heard/read conflicting stories.

I also would like to know a definate answer.
 
6.7 short block...5.9 top end. As long as the injector spray pattern is correct for the piston bowl, should be no problems...right???

Of course I have no real world experience to help. LOL

Epically posted via Tapatalk.
 
It works fine. I have ran a 6.7 short block 5.9 head, ECM and 03-04 injectors no problem with over 1K hp. I currently run a 6.7 block 6.7 head and 03-04 5.9 sticks with same great results. No extra machining or voo do chit like that. Use a 6.7 MLS gasket and machine both surface's to a RA of 20-30 also pull that head down with some 625 studs for best results. The MLS will seal the steam pockets on the block no problem providing the finish meets those RA specs.

Now running 6.7 sticks in a 5.9 head without doing prior machine work to get injector to seat properly NO. I have not tried that combo yet.
 
I should have also noted to run billet rods with that 6.7 if you plan on giving her hell. Knowing your posts im sure that will be a everyday thing for you.

Just to be clear when I said the MLS will seal fine. I meant the 6.7 gasket will have the steam holes but seals against the 5.9 head with no holes. That only holds true providing you have that 20-30 RA finish on both surface's. You can get away with a rougher RA but its a gamble when running your stuff hard.
 
Anyone have pics of 5.9 vs 6.7 pistons ? Didn't they go back to non re entrant on the 6.7's like the early 5.9's used ?
 
I seem to remember a thread about that, largely between RonA and Smokem...but I could be wrong as usual.
 
No pictures but yes pistons are back to the 03-04 design. Have not done a swap but I would lean towards 03-04 injectors though some believe the late model 5.9 injectors would work. Would also go with a 6.7 HG. I have never been totally sold on main studs for the 5.9's but the failures I have seen out of the 6.7's It and billet rods would be a safe bet with what I imagine your goals are.

Again I am no expert by any means..
 
I asked Weston to chime in on this thread.
While I have my cab off and the whole top of the motor....might as well consider all options.
Plus I have a line on a super cheap, super low mile motor....
 
Runninlean said:
No pictures but yes pistons are back to the 03-04 design. Have not done a swap but I would lean towards 03-04 injectors though some believe the late model 5.9 injectors would work. Would also go with a 6.7 HG. I have never been totally sold on main studs for the 5.9's but the failures I have seen out of the 6.7's It and billet rods would be a safe bet with what I imagine your goals are.

Again I am no expert by any means..
Click to expand...

I have early style injectors. My HP goal is a very conservative 850ish. With how light the truck will be that's more than enough power to get into trouble with.
OK....maybe 900.....LOL

I wonder if bowl size is also similar? Hmmm....damn Google isn't showing me very much useful info....
 
Wish I was home I could take some measurements.

I figured around 800-900 hp on fuel?
 
If that was a question...yes....somewhere in there. Projected weight is 56-5800 lbs.
More power would just cause more drivability issues.
 
Joesixpack said:
6.7 mandates billet rods in my books. Little tougher keeping the head on as well.
Click to expand...

I thought the rods were holding up well in the sub 1000 hp range?
Granted I haven't looked at much 6.7 stuff lately....

Care to elaborate on the head staying on ?
 
Yeah that would be a handful. Im trying to imagine driving the PS truck on the road and just makes my butt pucker...

Your truck is one of my favorite custom builds.
 
Have you searched? Weston posted pics of all the pistons just a few months ago. I dont remember the thread?? I would post them but they are on my computer at work.
 
I've heard that 6.7's have a higher cylender pressure than 5.9's. They can move some air rather easily. Longer stroke and larger bore. You going to get larger turbos to feed this????
 
With the CR and a 6.7 I would do rods. However if your not doing anything special to the engine, I would just run it until it blows, 6.7 engines anymore are getting much cheaper. Run it until the rods fail, meanwhile save up for a set of rods for the next one.
 
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